The closing table is not the finish line. It is the starting gun.
Most new commercial property owners walk away from closing focused on the right things: getting tenants settled, coordinating repairs, reviewing leases, setting up management. Those things matter. But while all of that is happening, a set of tax decisions are being made by default, and almost no one is paying attention to them.
The period right after acquisition is the most tax-valuable window you will have as an owner of that property. Here is why. Every dollar you paid at closing (purchase price, closing costs, due diligence fees, legal fees) goes into your depreciable basis. A cost segregation study reclassifies as much of that basis as possible from 39-year property into 5, 7, and 15-year property. That study can be done later, but it is cleanest and most defensible when done close to acquisition, before changes are made to the property. It is also the one time you can capture the full purchase price at once. That opportunity does not repeat.
The decisions you make early also determine what lands on your first return. Renovation work completed before December 31 generates deductions this year. The same work completed January 2 waits until next year. And a cost segregation study takes six to twelve weeks, which means if you wait too long to commission one, it will not be finished before year-end regardless of when you close. The 90-day window is not arbitrary. It is the lead time you need to make sure the right things happen before the calendar runs out.
This is the checklist your closing agent did not give you.
The in-service date is the date a property or improvement is ready and available for use in your trade or business, even if you have not started using it yet. For the building itself, this is typically your closing date. For improvements, it is the date the work is substantially complete. This date matters because it determines which tax year each deduction falls in. An HVAC system completed on December 30 generates depreciation this year. The same system completed on January 2 waits until next year.
The Checklist
The moment you take ownership, your in-service date begins and the depreciation clock starts. The IRS begins counting from this date. Every dollar of acquisition cost, the purchase price, closing costs, due diligence fees, legal fees, becomes part of your depreciable basis. That basis is what a cost segregation study will later reclassify to accelerate your deductions.
You probably had an inspection during due diligence. Pull that report back out and look at it differently. The inspector was telling you about problems. You are now looking at it as an opportunity list. Every aging system flagged on that report, HVAC units, roofing, electrical, lighting, plumbing, is a candidate for an upgrade that generates its own tax benefit.
The Section 179-D energy deduction covers three building systems: HVAC and hot water, interior lighting, and the building envelope: insulation, windows, doors, and roofing. Any of these systems that need replacing or upgrading may qualify for an additional deduction on top of standard depreciation.
The deduction rate is not a fixed number. It ranges from $0.58 to $5.81 per square foot depending on two factors: how much energy savings the improvements achieve, and whether the contractors performing the work paid Department of Labor prevailing wages. The prevailing wage threshold is the published DOL rate for each trade in your geographic area. It applies to both union and non-union contractors equally, and many already meet it without knowing it. At the maximum (50% or more energy savings with prevailing wage compliance), the deduction reaches $5.81 per square foot. At minimum qualifying levels, it starts at $0.58.
Solar is not covered by 179-D. It falls under Section 48 of the tax code: a 30% investment tax credit on installed cost. Solar also qualifies as 5-year MACRS property eligible for bonus depreciation.
At this stage, you are not committing to anything. You are simply identifying which systems are candidates so you can make informed decisions when you get to estimates.
This is the step most people delay, and it is the most important one to do early. A cost segregation study reclassifies components of your building from 39-year property into 5, 7, and 15-year property, dramatically accelerating your depreciation deductions. Components like flooring, cabinetry, electrical outlets, specialty plumbing, parking lots, landscaping, and exterior lighting all qualify.
Order early, before you complete improvements, so the study can capture both the acquisition cost and the improvement costs in a single engagement. Doing it later means a second study or a missed opportunity to reclassify the improvement components.
Now that you know which systems qualify for 179-D and which components the cost seg engineer wants to capture, get contractor estimates and prioritize the work. The sequencing matters: improvements placed in service before December 31 of the acquisition year qualify for that year's bonus depreciation. The same work done on January 2 waits an entire year. If you are replacing existing components rather than adding new ones, you may also qualify for a write-off on what you removed. See QIP and Partial Asset Disposition for how that works.
This is also where the cost segregation refund does its most important work. The year-one tax savings from your study, often $50,000 to $100,000 or more on a mid-size building, can fund the improvements directly. The study pays for the upgrades. The upgrades generate the next round of deductions. And if your renovation involves any engineering work, new processes, or experimentation, custom HVAC design, structural modifications, systems integration, there is a real chance R&D tax credits apply on top of everything else.
Once your qualifying energy improvements are done, a licensed energy assessor performs the 179-D certification. They use energy modeling software to verify that your improvements achieve the required 25% reduction in energy use compared to the ASHRAE 90.1 baseline. The certification is what makes the deduction official. Without it, the deduction does not hold up.
The assessor produces a signed certification document that becomes part of your tax file. This is not something your CPA can produce. It requires a qualified engineer or contractor licensed in the relevant jurisdiction.
Your Triple Star Strategy cost seg study results go to your CPA along with the 179-D certification and all improvement documentation. Everything lands on the same return. The accelerated depreciation from the study, the energy deduction from 179-D, and the bonus depreciation on improvements all work together, independently, with no conflict between them.
This is the return most property owners never file in year one, because they did not know the window existed, did not move early enough, or did not have a strategist rather than just a preparer in their corner. The difference between these two returns can be six figures on a single property. Before you sit down with your CPA, work through the five questions to ask before your next filing. They will help you walk in prepared.
Why the First 90 Days Are Different
There is no expiration date on most of these strategies. You can order a cost segregation study five years after you buy a building. You can do energy improvements in year three and claim 179-D then. None of this goes away permanently.
But the first 90 days are different for one reason: compounding.
Tax savings captured in year one get deployed in year one. They fund the improvements that generate the next round of deductions. They enter the compounding cycle, reinvested into a business or operation that generates 20, 30, even 50 percent returns, a full year before the same savings captured in year two. For the math on why that gap matters, see The Real Cost of Waiting.
A property owner who completes this checklist in the first 90 days after closing captures year-one tax savings, uses those savings to fund improvements, qualifies those improvements for additional deductions, and enters the compounding cycle twelve months before the owner who waits. The checklist does not create the opportunity. It captures the one that was already there.
The closing table is not the finish line. The first 90 days are where the real work happens. Quietly. Without urgency. With the right team in place.
Most property owners skip this checklist entirely. Not because they do not care. Because no one handed it to them.
Now you have it.
You Just Closed. Let's Start the Clock Right.
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